In top loading washing machines, the drive unit is commonly defined by an electric motor coupled to the drive shaft, directly or by means of transmission and fixed upon a support frame that is affixed or incorporated, in one piece, to the external lower side of a lower wall of the tub, wherein the assembly defined by the drive unit, vertical drive shaft and rotary basket remains fixed to the tub, conveying to the latter all the vibrations and oscillations caused by the spin of the basket during the washing and centrifugation operations, particularly when a centrifuge with eccentric masses results from a non-homogeneous distribution of the load of clothes inside the basket. In this common construction, the tub vibrates and oscillates in conjunction with the basket and the drive unit.
In the type of construction described above, the tub defines a structure that cannot be directly supported on the floor, due to the movement to which it is subjected during the machine operation. Thus, the provision of means of suspension that are able to absorb or dissipate at least a portion of the vibrating energy transmitted to the tub is required.
The solution known to circumvent this issue necessarily involves the provision of a cabinet encompassing the tub and the drive motor, the cabinet being supported directly on the floor. This arrangement includes the provision of constructive means of suspension, usually in the form of springs or other elastic elements, mounted on fixed rods, on the one extreme, in the region of the lower wall of the tank and at the other extreme, the upper inner portion of the cabinet.
Despite being widely used, this constructive solution of the prior art requires the provision of a cabinet to operate as a support structure for the remainder of the machine and also as a fixed housing, involving oscillating parts of the machine and operating as a defining element of the aesthetic aspect the machine. Besides being one more element in the construction of such machines, the cabinet leads to an increase in the dimensions of the whole assembly, as it has to internally accommodate the means of suspension, providing a circumferential backlash against the tub, still enough to prevent the latter to conflict with the cabinet during centrifuge operations with an eccentric load of laundry.
In another known solution, the drive motor is fixed to the vertical drive shaft passing through the bottom of the tub and carrying the rotary basket, the drive motor being attached to a support frame which is in turn backed by a base structure seated on the floor, by means of suspension including springs and shock absorbers. In this construction, the tub is mounted on a frame support, passing to oscillate and vibrate together with the basket and the drive motor when the machine is in operation. Although the means of suspension are fitted below the support frame, allowing the structural function of the cabinet to be limited in terms of support frame, the provision of a cabinet with sufficient height to encompass the whole of the tank is required in order to protect it visually and operationally during machine operation, as the tank oscillates and vibrates together with the basket and the drive motor.
Brazilian Patent Application No. PI0601707 (corresponding to U.S. Publication Application No. 2007/0251278) provides a top loading clothing washing machine that includes: a basic structure of a generally tubular form, to be inferiorly supported on a floor, a tank for containing a washing liquid and fixed on the basic structure, a support frame suspended within the basic structure; means of suspension absorbers of vibratory and oscillatory movements and connecting the frame to support the basic structure in order to keep the first suspended inside the last one; a drive motor disposed within the basic structure, fixed to the support frame and carrying a drive shaft extending vertically upward, into the tank and a rotating basket provided inside the tank and operatively and selectively associated with the drive shaft.